Smokeless explosive



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. P. G. DU PONT.

SMOKELESS EXPLOSIVE.

NU- 522,978. Patented Julyfl, 1894,

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FRANCIS G. DU PONT, OF WILMINGTON, DELAWARE.

SMOKELESS EXPLOSIVE.

SPECIFICATION forming part of Letters Patent No. 522,978, dated July 1'7, 1894.

Application filed September 26, v1 89S.

To all whom it may concern:

Be it known that I, FRANCIS G. DU PONT, a citizen of the United States, residing at Wilmington,in the county of New Castle and State of Delaware,haveinvented certain new and usefulImprovements in Explosives; and I do hereby declare the following to be a full, clear', and exact description 'of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in smokeless explosives to be used in rides, shot guns, and other arms, aswell as for other uses to which smokeless powder may be put; and it consists in an improved process for producing a smokeless explosive from nitro-cellulose, which consists in mixing in suitable proportions with the nitro-cellulose, when it is suspended in an oil, such as hydro-carbon oil, a solvent of the nitro-cellulose which, although it may be miscible with the suspending oil, is still capable of exerting a solvent action upon the nitro-cellulose, such as acetone and some of the high boiling point ketones, as dipropyl ketone, and subsequentlyV hardening the grains thus produced, and which will be hereinafter fully described, and particularly pointed out in the claims.

In the joint application of myself and Pierre S. du Pont for Letters Patent for improvements in explosives, tiled December 21, 1892, Serial No. 455,901, patented August 22, 1993, No. 503,583, a process for producing a smokeless powder was described, which consists in granulating the nitro-cellulose by agitating therewith, when suspended in a liquid not a solvent ofthe same, a solvent of the nitro-cellulose not soluble to any great extent in the liquid'used to suspend the nitro-cellulose, and

vsubsequently hardening the grains thus produced. In said application, while it was stated that any suitable solvent might be used to form the granulation thus produced, which was not soluble to any great extent inl the liquid used to suspend the nitro-cellulose, attention was especially called tothe nitro-compounds of the aromatic group, of which nitrobenzole was mentioned as a type, as being suitable solvents; and while it was stated that any suitable liquid, not a solvent of the nitrocellulose, might be used-to suspend the same,-

sehn No. 486,519, (No specimens.)

the grauulation was described'as taking place When the nitro-cellulose was suspended' in Water.

I have discovered that a parallel result may be accomplished by suspending the nitro-cellulose in liquids of the nature of oils, such as hydro-carbon oils, of which kerosene, benzine, and gasoline may be mentioned as especially suited for the purpose, and by forming the' granulation ofthe nitro-cellulose by agitating with the same, thus suspended in an oil, a solvent of athe nitro-cellulose which, though it may be miscible with the suspending oil, is still capable ofexertinga solvent action upon the nitro-cellulose. It is thus not necessary that the solvent employed to granulate 'the nitro-cellulosebe insoluble to a greater or less extent in the liquid used to suspend the same, but only that the relative attraction of the solvent for the oil and for the nitro-cellulose besuch that there is a stronger tendency for nitro-cellulose, thrown into a solution of the solvent and the oil, to take the solvent, than for the oil to hold it. Ot such solvents, acetone'and some of the high boiling point lieto/nes may be mentioned as examples.

Nitro-benzole cannot be conveniently used when an oil is used to suspend the nitro-celluldse, for the reason that it is so soluble in oils that, unless added in great excess, it will not leave the oil in suiiicient quantity to form the granulation with the nitro-cellulose. In any case, the` grains formed are imperfect. Nor can such a solvent of nitro-cellulose as acetone be used when the nitro-cellulose'is suspended in water, because acetone is so soluble in water that it will not leave the water to cause the required granulation. But when the nitro-cellulose is suspended in an oil, and a solvent of the same is used which, although it may be completely miscible With'the oil, will yet leavev the oil to act upon the -nitrocellulose, a perfect granulationresults. The grains thus formed are ot the same general-.character as those produced by the process described in the joint application of myself and Pierres.-

du Pont, to which reference has been made, that is, of uniform size, and hard and round ICC) but are somewhat denser, and more compact. f

The increased advantage gained by the use of an oil, such as kerosene oil, in which to suspend the nitro-cellulose, lies in the fact from the grain.

that thereby a more even and uniform dis' tribution of the particles of nitro-cellulose throughout the liquid is obtained, and the granulation therefore takes place under more advantageous circumstances.

The apparatus employed in carrying out my process is fully represented in the drawings accompanying and forming a part of this application, in which- Figure 1, taken on the line mFig. 13,1001;- ing' in the direction of the arrow, is a View of the churn in which the mixture of the nitrocellulose with the solvent takes place. Fig. 1a isa sectional view of the same. Fig. 2 is a sectional -view of the rotating barrel in which the grain formed, in the churn shown in Figs. 1 and -1a is rounded and hardened. Fig. 3 is aview of the still in which the oil is removed Before proceeding with a description of 'my process, I shall describe the vapparatus used in carrying it out. v

Referringto the drawings, and especially 1 to Figs. 1 and 1, Arepresents a churn, in

which, on a shaft B, are mounted the blades b, each of which is formed "with a notched outer surface to promote currents from side to sidein the contents of the'churn during the rotation of the blades. Steam inlet pipes C are provided, which are relatively small in diameter, so that the steam will be well distributed through the contents'ofthe churn,

and a single steam outlet pipe D, which leads to the refrigerating coils E, where the vapors it conducts may be condensed. The pipes C are bent upward or otherwise formed so as to prevent the escape of the contents of the churn through the same.

A provided for the admis'ssion of material, and

an opening C to aid in flushing the interior of the churn when .desired Test cocks 1 1 are also provided, in order that the condition of the contents of the churn may atany time be ascertained. 1

I n Fig. 2 the rotating barrel is'repre's'ented in which thehardenin g of the grains produced by the granulation in `the churn shown in Figs. 1 and lais carried on.'4 G is the rotatcentral hollow axis I, journaled in the supports t' t'. The barrel G is surrounded by a jacket I-l, also mounted on the axis I, and

connected with the barrel G so as to revolve with it. Between the' jacket andA thebarrel, a supply -of water is kept constantly Aflowing, while the grains of explosive are being hardened. The water, which is'heated to a suit` able temperature, is introduced through the supply pipe 2, leading into -one end of the central axisv I, and passes' into the space between the jacket and the .barrel through the openings 3 in said axis, its low through the axis being interrupted by the partition 4 'formed in the same.. After circulating through the jacket, the water passes out through the openings 5, formed at the other that the fall of the end of the axis, into the axis I, and is en Y be conducted away. A stopper 8 prevents any water from entering the pipe at this end. The water inlet Ipipe 2- is provided with a stufiing box or gland 9, which permits the axis to revolve around itV without leakage, and the s'topper'S is also so constructed as to permit the axis I to revolve around the pipe 7 without permitting any escape of vapors. An opening'K is provided for the introduction and removal of material.

I have made separate 4application for Letters Patent for the form of still shown in Fig. 3, said application being dated April 15, 1893, Serial No. 470,347, but I will-briefly describe the same, sol that its constructionand operation may be understood.

L represents a still, of any convenient size and construction, around the lower portion of which is placed an encircling steam jacket M, provided with steam inlet and outlet pipes.

The pipe N, at the apex of the conical bot' tom of the still, serves for the introduction and removal of material. The still isprovided with a lconical top O, around which is l placed the jacket P, which is. provided with water inletv and outlet pipes, and between which, and the t 0, a stream of cold water is constantly flowing when the still is in opv eration. An opening F is The outlet Q is for the conduction. of .ivapors escapingfrom the still to any suitable condenser, which condenser is so arranged is backward into the still, so as to drain con` densed products into the still head. Inside of the top O, and of acorrespo'nding shape, is suspended the inner shell o r cone R, the

function.' of which is to prevent thedistiilate fo o pipes leading to the same IIO coming from the condenser from falling' into the still, and to determine its delivery, as well as that of all the vapors condensed in the still head, into the annular trough S, which surrounds the interior of the still at the base 'of the still head.'

The pipe T atiords an exit from this trough in-to the outer vesselU, which answers as a" reservoir for the distillate. This reservoir has a conical bottom, and a pipe at the apex ofthe same, by means of which the reservoir may be emptied when desired. An outlet pipe V is also provided on the side of the reservoir,- from whi ch may be drawn from time to time the oil which has collected. Besides the connection afforded by pipe T, the reservoir is also connected with the still by the Siphon pipe W, the lengthsof the branches of which are so arranged that the water which collects in the bottom of the reservoir Uwill 'be automatically returned to the still L. Stop cocks are provided to control the passage through the pipesleading to and from the still and reservoir.

Referring row to my process, I have found that in order to obtain a perfect granulation, it i's necessary as a preliminary step to thoroughly dry the nitro-cellulose, before suspending the same in oil. The form of nitrocellulose which I preferably use is that known as tri-nitrocellulose or gun cotton. Gun cotton, as usually prepared, contains a small percentage of Water, as dry gun cotton is exceedingly dangerous to handle and store. As in my process, however', I suspend the gun cotton in oil, it is necessary, on account of the refusal of oil and water to mix, to remove this water, in order to obtain an even d-istribution of the particles of the gun cotton throughout the oil. I dry the gun cottonafter t'he mannerdescribed in my applicationfor Let- I ably ters Patent for an improved process for drying nitro-cellulose, led June 15, 1893, Serial No. 477,667, by placing the wet gun cotton in a still filled with an oil, such as kerosene oil, and then distilling oli theoil andthe water together. The distillation may be performed in such a still as that shown in Fig. 3 of the drawings accompanying this application,the action of which will be fully explained when the step of my present process is reachedin which it is used. In this manner, all of the water is removed from the gun cotton, and the same is obtained perfectly dry, although impregnatedv with the oil in which it hasbeen placed. The presence of this oil is, however,

knot objectionable in my process.

Proceeding now with my process, I fill the churn A to the desired height with oil, and then add thereto nitro-cellulose in the proportion of ten pounds of dry nitro-cellulose to fifty pints of oil.

use kerosene oil,--free from any heavy oils-which distills at about 212 Fahrenheit, and which maintains its boiling point pretty constant at that ligure. Although the oil may contain lighter products, it must not contain non-volatile matter, as in the latter part of my process it is to be completely removed from the grains formed. The nitro-cellulose is suspended in the oil by the rotation of the blades of the churn, and, when fully suspended, acetone is run into the churn in the proper proportion, and the agitation continued until granulation takes place from the action of the acetone upon the nitro-cellulose. The proper proportion in which to add.v the acetone depends somewhat ,upon the grade ofA oil used. When a light oil is used,it should be added in the proportion of thirty pints of acetone to ten pounds of nitro-cellulose, the latterhaving been added to the amount of kerosene hereinbefore mentioned. VVhen however, a heavier oil is used, the same proportion of oil and nitro-cellulose will be required, but only aboutl twenty-five pints of For such oil I prefer.

acetone. Of course these proportions can be Varied, but those given are well suited for the purpose, and indicate with sufficient definiteness the variation of the quantity of acetone to be added when dilerent grades of suspending loils are used. The reason for such variation is the differing solubility of the acetone in the different gradesof oil. The heavier the oil, the less the solubility of the acetone therein, and consequently the less the amount of the same which remains in solution in the suspending oil throughout the granulation process.

When the gran ulation is complete, the contents of the churn are removed, and. placed in the rotating barrel shown in Fig. 2. y This barrel is now rotated for a time without the application of any heat, the grains being thus partially compacted and rounded. Water, heated to a temperature a little lower than the boiling point of-the solvent for the nitrocellulose which is used, is then circulated through the jacket surroundingl the' barrel, and the rotation continued until an entire separation of the excess of acetone from the grains has been accomplish-ed. Acetone, the

solvent which I have described as being used, boils at about 165c Fahrenheit. When acetone is used, the proper temperature of the water is about 150 Fahrenheit. The vapors resulting from the application of this heat are conveyed away through pipe 7,a vacuum pump being applied to aid the carrying away of the same as rapidly as formed. The hard- IOO ening and rounding of the grain thus take place during the removal of the excess of solvent, and while the grain is still immersed in oil, the rounding action appearing to go on better with the oil than without the same. Thegrain is now completely formed, free from excess of acetone, and in a. hardened condition. It is, however, saturated with oil. To remove this oil, the grain is taken from the barrel, the excess of oil strained olf, and

Ithe oily grain placed in the still shown in Fig. 3, which is partially tilledwith water. The temperature of the still is `now raised, through the admission of steam into the steam Vjacket surrounding the lower Aportion of the same,`untildistillation commences. Asthe boiling point of the oil and the water is about the same, they pass off tgether, being condensed on the inner shell or cone R, and from thence falling intol the annular trough S, from whence they are conveyed by the pipe T into the vessel U. A separation here takes place, due to the differing specific gravities of the oil and the water, the oil being drawn '0H through the testl cock V, and the'water being automatically returned to the still by the siphon W. There is thus no loss of oil, and

should any ofthe solvent have remained dissolved in 4the oil, it will also be recovered.

The grains formed by this process have the same general character asA those produced when nitro-benzole is used to eect granulaused, on account of the change in boiling point and specific gravity of the same. Thus when acetone is used, since its boiling point' is much less than that of the oil, it will pass off first in the freeing of the solvent from the excess of solvent and the oil, while if a solvent is used which has a boiling point higher than that of the oil used, the oil will pass off first. If an oil is used which is heavier than water, the end of the siphon pipe extending down in the reservoir will have to be cut od so as only to return the lighterportion of the distillate, and the oil can be drawn olf from the bottom of the reservoir. These variations, however, do not affect the essential feature of my process, which consistsin suspending the nitro-cellulose in an oil, and then granulating the same by agitating therewith` a solvent of the nitro-cellulose which, although soluble in the suspending oil, will leave the same to act upon the nitro-cellulose.

Among the high boiling point ketones that can be used in carrying out my process, I may mention methyl tri-methyl carbon ketone, which boils at 105 centigrade; dipropyl ketone, which' boils at 145 centigrade; methyl propyl ketone, which boils at 100 centigrade; and a ketone formed bythe dry distillation of calcio bntyrate, thought to be ethyl-propyl ketone, which boils at 128 centigrade.

The explosive force of the grains produced,

can of course be lessened, if desired, by the addition of any of the ordinary moderating agents. Such operation can be performed, for instance, in the manner described in the 'patent of myself and Pierre S. du Pont, No. 503,583, above referred to, and the moderating agents therein specifically mentioned may be used.

I do not confine myself to the particular apparatus described, nor to the particular proportions of ingredients mentioned, nor to the use of the particular oil and solvents stated, as these may be varied without affecting the merits of my invention.

What I claim as new, and desire to secure by Letters Patent, is-

1. The process of manufacturing a smokeless explosive, which consists in suspending nitro-cellulose in a suitable liquid not a solvent of the nitro-cellulose, granulating the nitro-cellulose by agitating therewith in suitable proportions asolvent of the same which, though soluble in the suspending liquid is still capable of exerting a solvent action upon The evapo-V the nitro-cellulose, and subsequently hardening the grains thus produced, substantially as described.

2. The process of manufacturing a smokeless explosive, which consists in suspending nitro-cellulose in oil, granulating the same by agitating therewith in suitable proportionsv a solvent of the nitro-cellulose which, though soluble in the suspending oil,"s still capable of exerting a solvent action upon the nitro cellulose, and subsequently hardening the grains thus produced, substantially as described.

3. The process of manufacturing a smokeless explosivo, which consists in suspending nitro-cellulose in a hydro-carbon oil, granulating the same byagitating-therewith in suitable proportions a solvent of the nitro-cellulose which, though soluble in the suspending oil, has a stronger. affinity for nitro-cellulose, and subsequently hardening the grains thus produced, substantially as described.

4." The process of manufacturing a smokeless explosive, which consists in suspending Dito-cellulose Ain a hydro-carbon oil, gran ulating the same by agitating acetone therewith in suitable proportions, and subsequently hardening the grains thus produced, substantially as described. l

5. The process of manufacturing a smokeless explosive, which consists insuspending nitro-cellulose in oil, granulating the same by agitating therewith in suitable proportions a solvent of the same which, though soluble in the suspending oil, is still capable of exerting a solvent action upon the nitro cellulose, hardening the grains thus produced byV agitation, accompanied by removal of the excess of solvent, and finally removing the oil from the grains, substantially as described.

6. The process of manufacturing a smokeless explosive, which consists in suspending nitro-cellulose in oil, granulating the same by agitating therewith in suitable proportions a solvent of the same, which though soluble in the suspending oil, is still capable of exerting a' solvent action upon the nitrocellulose, hardening the grains thus produced by rotation, accompanied -by removal of the excess of solvent,and finally removing the-oil from th'e grains, substantially as described.

7. The process of manufacturing a smokeless explosive, which consists in suspending nitro-cellulose in oil, granulating-the same by agitating therewith in suitable proportions a solvent of the same which, though, soluble in the suspending` oil, is still capable of exerting a solvent action upon the nitrocellulose, hardening the grains thus produced by rotation while immersedv in the oil, accompanied by a removal of the excess of solvent, and finally removing the oil from the grains, substantially as described. i

8. The process of manufacturing a' smokeless explosive, which consists in suspending nitro-cellulose in a hydro-carbon oil, granudating the same by agitating therewith in A suitable proportions a solvent of the nitroscribed.

ceilulose,which,thoughso1uble in the susthe oil from the grains, substantially as dero In testimony whereof I aix my signature in pending oil, is still oapable of exerting a Solv? presence of two witnesses.

ent action upon the nitro-ce11u1ose,harden ing the grains thus produced by rotation While immersed in thel oil, and then by continued rotation accolp'anied by the remova et the excess of sol-veut, and finally removing FRANCIS G. DU PONT.

Witnesses:

THOS. .1. BOWEN, .T r., .f HENRY J. CRIPIYEN. 

